1. Field of the Invention
The present invention relates to an apparatus for and a method of generating a tomographic image.
2. Description of the Related Art
Recently, apparatus have been proposed in the medical field for irradiating an affected area in a subject such as a human body with radiation from a radiation source, which is moved to different positions to capture respective radiographic images of the affected area, and for processing the obtained projection image data into a desired tomographic image of the affected area for detailed observation of the affected area.
Japanese Laid-Open Patent Publication No. 2004-121853 discloses a method of and an apparatus for reconstructing an image in an external area of a field of view by enhancing partially sampled field-of-view data using fully sampled field-of-view data. Since the disclosed method and apparatus is capable of expanding the range that can be represented as a tomographic image, the disclosed method and apparatus is highly convenient for use in diagnostic applications.
There have also been proposed various processes for minimizing artifacts (false images) in tomographic images by improving a process of calculating partially sampled field-of-view data.
Japanese Laid-Open Patent Publication No. 2005-152658 discloses an apparatus for and a method of assigning irregular coefficients to respective sliced positions (equivalent to respective pixels) of backprojection data, and performing a product-sum operation on acquired projection image data in order to generate a tomographic image.
Japanese Laid-Open Patent Publication No. 2008-200273 reveals an apparatus for and a method of replacing the values of pixels, which are judged as forming an incompletely focused area (partially sampled field-of-view data), with a prescribed constant value in order to fill in such pixels.